Improvement in parallel rulers



UNITED STATES PATENT QFFIGE.

WILLIAM B. MASON, OF BOSTON, MASSACHUSETTS.

IMPROVEMENT IN PARALLEL RULERS.

Specification forming part of Letters Patent No. 34,814, dated January 14, 1873.

To all whom it may concern:

Be it known that I, WILLIAM B. MAsON, of

Boston, in the county of Suffolk and State of 'set, and gaged at any desirable distance apart,

and when set, maintained in such fixed position; and my invention consists in combining with two rectangular bars, so connected by levers pivoted to each that, as the bars are moved to vary their positions, their lines of movement shall always be in parallelism, an arm or limb provided with a graduated scale denoting inches or fractional parts thereof, and means for locking or maintaining the parts when gaged in the desired position; and my invention further consists in combining, with the pivoted levers, the graduated arm, and the rectangular bars, two clamping devices, by which the bar to which they are affixed may be removed and another of any desirable length substituted in place thereof.

In the said drawing, a and 1) denote two rectangular bars, which may be of desirable width and length, such bars being connected by two short links, 0 d, of equal length. 0 e are two clamps, which are, respectively, pivoted at their inner ends to the extremities of the links 0 and cl. These clamps are so formed as to embrace one of the bars-viz., aand each is provided with a setscrew, f or f, by which the bar is firmly held in position, the object of such clamps being to enable the bar to be changed and another of any desired length substituted therefor. g is a metallic arm, which turns on the shank of the screw f as a pivot. This arm has on its face a scale of divisions, which may be inches or fractional parts thereof, the same also having a series of holes arranged near one edge thereof, and corresponding with the graduations of the scale. his a spring-catch lever, carrying on its inner end a stud to enter any desired hole in the graduated arm, which is so graduated as to indicate, when the stud is in the hole in line with any numeral or subdivision thereof, the distance apart of the outer edges of the two bars ab.

Having described my invention, what I claim is- The clamps e e and their set-screws f f, in combination with the links 0 d of the bar I), the graduated arm 9, and its catchlever h, substantially as and for the purpose stated.

XVILLIAM B. MASON.

Witnesses:

F. P. HALE, E. A. LOCKE. 

